The Cutting Edge: COMPUTING / TECHNOLOGY / INNOVATION : DNA’s Most Important Use: Diagnosis
DNA analysis might grab headlines when it’s used in criminal cases such as the O.J. Simpson murder trial, but it’s most important day-to-day use will likely be as a diagnostic tool. Already, DNA analysis can reveal the presence of certain hereditary disorders, and as biologists decipher more of the information in our genetic code, DNA’s diagnostic potential will expand. To make use of this knowledge, however, doctors will need a fast, low-cost and low-priced method of conducting DNA analysis. Scientists at the UC Berkeley believe they have taken a big step in that direction by miniaturizing one of the crucial steps in DNA analysis, using what they call “DNA analysis-on-a-chip.”
Today, DNA profiling is a complex and time-consuming business. Basically, it involves extracting DNA from blood, semen or tissue, amplifying it by perhaps a million times, cutting it into many pieces, tagging those pieces that contain a specific marker, then separating the pieces along the length of an electrophoresis gel. These gels, in which particles are suspended in a liquid, are one of the major bottlenecks in DNA analysis: it can take weeks for the DNA fragments to separate out into distinct bands that can be detected using radioactive analysis methods.
The UC Berkeley scientists have constructed a miniaturized gel about an inch long and only two- thousandths of an inch wide--50 times smaller than the standard slab gels. With this gel, analysis that might take weeks can be done in just two minutes.
The gel-on-a-chip is created by chemically etching microscopic channels into a glass plate and covering them with a second glass plate. When filled with gel, DNA fragments migrate down the channel at a rate determined by their size. Under a grant from the Advanced Technology Program of the National Institute of Standards and Technology, Molecular Dynamics of Sunnyvale, Calif., and its partner, Affymetric of Santa Clara, Calif., will develop miniaturized DNA diagnostic systems, with help from the Berkeley scientists.
He’s Not My Brother: Bone-marrow transplants can mean the difference of life or death for leukemia patients. But successful transplantation requires that certain characteristics of the donor and the patient’s immune system be closely matched to avoid rejection and other complications. And fewer than 30% of leukemia patients who might benefit from a bone-marrow transplant have a matched donor even among their siblings, while just 3% to 5% manage to find such a person among other relatives.
Now researchers from the Weizmann Institute in Israel and Perugia University in Italy have a developed a method that may significantly improve the chances for a successful transplant from unmatched donors. The key to the new technique is megadoses of donor marrow. Such doses appear to be effective by giving donor cells an edge in their competition with the patient’s own cells, thus minimizing the risk of rejection.
To obtain these large amounts of marrow, researchers gave donors hormonal drugs called cytokines, which increase the number of cells in the blood by mobilizing them from the bone marrow. The amount of marrow obtained this way can be seven to 10 times greater than from the bones. The marrow is treated with a soybean-derived lectin to eliminate white blood cells that would otherwise attack the recipient’s tissues. While the treatment has only been tried on people with leukemia, in the future it may be modified to treat non-cancerous blood disorders such as sickle-cell anemia.
Digital Dairy: What database contains such keywords as “genetic improvement,” “reproduction” and “milk management”? Try the National Dairy Database, which lets dairy farmers search for up-to-date information on dairy-cattle management and marketing and health aspects of dairy products, and also offers software programs on budgets, soil, fertility and herd health.
The CD-ROM database is a result of a decade of work on a USDA-funded project coordinated by the University of Illinois at Urbana-Champaign. The database, which is being sold through the University of Wisconsin at Madison for $99, will be updated each year..
More Fog: Caltrans wants Californians to know that they have a fog warning system similar to the one from the Georgia Department of Transportation described in “In Development” on Oct. 19th. The program, which includes the use of high-tech roadside weather stations, visibility sensors and closed-circuit TV, focuses on the seasonal fog in the Central Valley. Data is collected along U.S. 99, relayed back to the Caltrans headquarters in Fresno and then used to update electronic message signs and warn motorists via radio.
